Alarm devices



April 1967 R. H. VOIGT ETAL 3,315,244

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INVENTORS.

ROBERT H. VOIGT JACK D. OSBORNE United States Patent 3,315,244 ALARM DEVICES Robert H. Voigt and Jack D. Osborne, Milford, Mich, assignors to ASECO, Incorporated, Milford, Mich., a corporation of Michigan Filed Jan. 13, 1964, Ser. No. 337,444 33 Claims. (Cl. 340-227) The present invention relates to electrical control cirunits for producing a plurality of audibly distinguishable alarms, particularly to a multiple purpose alarm device which may be actuated from a remote point to warn of impending danger and which will also produce an audibly distinguishable alarm in the event of fire or smoke within the vicinity of the device, and more particularly to such an alarm device incorporating a solid state device for its major control function.

The National Emergency Alarm Repeater (NEAR) System has been developed by the Office of Civil and Defense Mobilization to provide for the use of existing power lines to provide a means of warning the population in the event of enemy attack. Generating equipment will transmit a signal in the form of a short burst of 210 or 270 cycles per second frequency superimposed on the 60 cycle power normally transmitted through the power lines. A receiver unit which is plugged into an ordinary wall receptacle will actuate a buzzer or bell upon receipt of the signal of sufficient duration. The term NEAR voltage has been used to designate this actuation signal and will be so used hereinafter.

Certain safeguards must be built into the receiving component of the NEAR system to prevent false alarms. Means must be provided for delaying the sounding of the alarm for 10 to 25 seconds after receipt of the NEAR voltage, to prevent false alarms that could be caused by interference on the power lines such as lightning, switching transients, etc. Also, the time delay means cannot be cumulative to a series of transients or coded NEAR voltage signals of 2 to 5 seconds duration each, which might accumulate to result in a false alarm. The time delay means must be independent of power line voltage, ambient temperature, humidity, and NEAR voltage amplitude, within the to 25 second tolerance specified.

A copending application Serial No. 179,058, filed March 12, 1962 and now Patent No. 3,149,365 discloses a receiver unit for the NEAR system which is provided with means for producing an alarm signal in the event of a fire which is readily identifiable from the base NEAR alarm signal. The receiver unit of the aforementioned application incorporates a time delay means which utilizes an expandable fluid cell normally held in a closed position by a spring loaded solenoid. While such a receiver meets most of the necessary requirements, several disadvantages have been discovered with respect to this receiver. First, an audible click is sounded each time a NEAR voltage of sufficient amplitude is received. Secondly, the solenoid is subject to wear since it will respond to the presence of NEA-R voltage, even if the duration of the NEAR voltage is not sufiicient to result in an alarm.

Another copending application, Serial No. 267,655, filed March 25, 1-963 and now US. Pat. No. 3,284,791, describes and claims a NEAR receiver incorporating a solid state or transistor timing device. Such a receiver is not subject to wear or degradation when in a standby condition and undue wear does not result when coded pulses of NEAR voltage are received by the device. 'While this receiver has proven quite satisfactory, it does not incorporate a fire alarm system.

The present invention discloses an improved receiving component for the NEAR system incorporating a solid state or transistor timing device and having means which will also produce an alarm signal in the event of fire or smoke and which alarm is readily idenitfiable from the base NEAR alarm signal.

It is an object of the present invention to produce an effective multipurpose alarm system by providing means producing audibly distinguishable alarm signals.

It is another object of the present invention to produce a reliable signal receiving and a multipurpose audible warning device by providing an ultra sensitive signal detecting portion and a transistorized control and time delay portion.

It is still another object of the present invention to provide a combination NEAR receiving component and fire alarm device by providing means producing one alarm signal upon actuation by the NEAR voltage signal and producing another and different alarm signal in the pres ence of fire or smoke.

it is yet another object of the present invention to provide improved combination fire alarm NEAR receivers by providing circuitry for such devices isolating the fire and smoke detecting portions of the device from the NEAR signal detecting portions.

Still further objects and advantages will readily occur to one skilled in the art to which the invention pertains upon reference to the following drawings in which like reference characters refer to like parts throughout the several views and in which FIG. 1 is a diagrammatic view of one preferred embodiment of the present invention, and

FIG. 2 is a diagrammatic view of another preferred embodiment of the present invention.

Description Now referring to the drawings for a more detailed description of the present invention, preferred alarm devices r are illustrated diagrammatically as comprising power line input contacts, generally designated at 10, adapted for insertion into an ordinary A.C. wall receptacle (not shown) and having plug prongs 12 and 13 which are preferably connected to power lines 14-15 as shown. A neon lamp 16 and a dropping resistor 17 are connected across the power lines 14-15 to indicatethat sufficient line voltage is present to operate the device.

A resonant circuit, generally indicated at 20, is connected across the power lines 14-15 and preferably includes a capacitor 21 and an inductor 22. A mechanical resonant reed member 23 and a fixed contact 24 are disposed within the magnetic field of the inductor 22 to form a discharge switch across a first capacitor 27. The first capacitor 27 is connected across lines 14-15 and is charged from a rectifying diode 25 through a resistor 26 in the line 14 as shown.

The capacitor 21 and inductor 22 form a series tuned electrical resonance circuit (L-C circuit). The capacitive reactance (X of the capacitor 21 is substantially the same as the inductive reactance (X of the inductor 22 at the predetermined NEAR signal frequency; thus on receipt of the NEAR voltage the two reactances cancel one another, being (degrees) out of phase, and the maximum NEAR voltage energy flows across the inductor 22. This maximum signal energy results in a substantial increase in magnetic energy across the air gap of the inductor 22 causing the reed member 23 which is disposed within this gap to vibrate. The resonant reed member 23 is mechanically tuned to the NEAR voltage frequency and the reed 23 will resonate with sufiicient amplitude to engage the fixed contact member 24, instantly discharging the first capacitor 27 A second capacitor 30 is also connected across the lines 14-15 as shown and this with the resistors 26 and 33 form a voltage divider network. In the absence of NEAR voltage the capacitor 30 is at maximum electrical charge )tential, being charged from the pulsating D.C. source the rectifying diode 25, through resistors 26, 33 and t and blocking diode 34. When the capacitor is disiarged by the reed member 23, engaging the fixed conct member 24, the voltage potential across the capacir 27 will drop from approximately 37 volts to less than 1e volt in the first few cycles of reed oscillation.

At the moment that the capacitor 27 is discharged, ten the voltage potential at the junction 38 between restors 26 and 33 will drop to less than 1.0 volt with reect to the power line and since there is no longer a )urce of charging energy for the capacitor 39, it too will egin to discharge through the resistor circuit connected :ross lines 14-15 and comprising resistors 32 and 35, iermistor 37 and resistor 36.

A parallel discharge path is also provided for capaci- )r 30 through a PNP transistor 41 from its base 42 to s emitter 43, and thence through bias resistor 44 to the ne 15 as shown. The transistor 41 could be of an NPN we in which case the charging polarities and biases ould be reversed.

An alarm relay coil 46 is connected across the lines 4-15 through resistor 40 and in parallel, with a series ircuit comprising resistors 38A and 44 and the emitter -3-collector 47 circuit of the transistor 41. A capacitor '9 shunts the alarm relay coil 46. An alarm relay ciruit is connected across lines 14-15 and comprises an tlarm coil 49 and an alarm relay generally designated at 38. The alarm relay 48 comprises a fixed contact 59 ll'ld an armature 51 disposed within the magnetic field )f the relay coil 46. The armature 51 is operable to engage the contact 50 and close the alarm circuit when the :oil 46 is energized. A clapper 52 is disposed within the nagnetic field of the alarm coil 49 in a position to strike .he control box (not shown) of the device when the coil 49 is energized, thus producing an audible alarm.

With the device in standby condition and without the NEAR voltage signal present at the input plug 10, the

PNP transistor 41 will have a negative voltage on the base 42 with respect to the emitter 43 and the transistor 41 will conduct. Current flow will then be directed from the line 14 through the resistors 40 and 38A and through the transistor 41 to the line 15. Little current will flow through the relay 46.

As capacitor 30 begins to discharge at the presence of NEAR voltage as heretofore explained, the negative control bias on the base 42 of the transistor 41 will decay at a predetermined rate which depends upon the size of the capacitor 30 and the values of the resistors 32, 35, 36 and thermistor 37. Thermistor 37 is a temperature sensitive resistor with a negative temperature coefiicient and is used for temperature compensation of transistor 41. The negative bias on the base 42 will continue to drop as long as NEAR voltage is present across the resonant circuit 20. In a period of 10 to 25 seconds, this bias on the base 42 will shift from negative to a positive bias with respect to the emitter 43.

The change in bias will cause the resistance between the emitter 43 and the collector 47 of the transistor 43 to increase substantially and sufficient current flow will be diverted through the alarm coil 46 to cause the armature 51 to engage the fixed cont-act 50, thus energizing the coil 49 to cause vibration of the clapper 52 to produce an audible alarm.

The resistor 40 is a dropping resistor and must be adjusted in value to agree with the operating parameters of the transistor 41 and the alarm relay coil 46. The capacitor 39 acts to filter out fluctuations in the pulsating D.C. current from the rectifying diode 25.

The resistor 32 delays the charging of the capacitor 30 so that a negative bias will appear almost instantly at the base 42 of the transistor 41 when the device is first plugged in or after line power is returned following a power failure. In the absence of resistor 32, a positive bias would appear on base 42 for a few seconds when the power is returned to the lines and an alarm would sound. During the alarm cycle, the positive bias on the base 42 with respect to the emitter 43 is produced by resistor 44 in series with emitter 43 with the return to the base 42 being completed through resistor 36. This positive bias could also be produced with a voltage divider network across the lines 1415 on the D.C. side of rectifying diode 25 with the resistor 44 being placed between the emitter 43 of the transistor 41 and a positive junction on the resistive voltage divider.

The blocking diode 3'4 prevents current flow from the capacitor 30 through resistors 32 and 33, the reed member 23 and the contact member 24 when the NEAR voltage is received. In the absence of the diode 34, the capacitor 30 would discharge immediately upon receipt of the NEAR voltage and the negative bias would be lost on the base 42 of the transistor to sound the alarm with out the necessary delay.

Referring specifically to FIG. 1, a fire detecting circuit is connected across lines 1415 on the AC. side of rectifying diode 25 and comprises a dropping resistor 86, a diode 91, limiting resistor 88 and a series parallel network comprising a capacitor 93, a resistor 97 and normally closed bimetal thermostat switch 96. The series connected resistor 9'7 and thermostat switch 96 shunt capacitor 93 as shown. A neon lamp 92 connects the fire detecting circuit to base 42 of the transistor 41 and through the resistor 36 to line 15.

In normal operation the thermostat switch 96 will be closed and the neon lamp 92 will not reach a sufficient voltage to ionize and therefore will not conduct to the base 43 of the transistor 41. In the event of fire or a sufficient temperature to open thermostat switch 96, the shunt is removed from the capacitor 93 and voltage Will build up until the neon lamp 92 conducts to place an immediate positive bias on the base 42 of the transistor 41 sufficient to increase the resistance between the emitter 43 and the collector 47 of the transistor 41 and to thereby inc-rease current flow through the relay coil 46 and actuate the clapper 52 as heretofore explained.

The alarm which is sounded in the event of fire, unlike the continuous alarm sounded upon receipt of the NEAR voltage, will be of short duration since upon ionization of the neon lamp 92 the capacitor 93 will discharge through the lamp 92 and the voltage potential across the capacitor 93 will be momentarily lost, thereby decreasing the voltage potential across neon lamp 92 so that it will no longer conduct. This cycle will be repeated as long as the thermostat switch 96 remains open so that a series of alarms will be sounded.

Diode 91, resistor 88 and capacitor 93 with neon lamp 92 in eflect provide a relaxation oscillator which, as long as the thermostat 96 remains open, will provide a build up of voltage potential that will discharge through the base 42 of transistor 41 each time the ionization potential of neon lamp 92 is reached.

It is clear that in place of thermostat switch 96 a positive temperature coefficient thermistor could be used to detect an increase in the temperature since this thermistor would reach a resistance at a given temperature to in efiect remove the shunt from capacitor 93 and build up the voltage potential across neon lamp 92 to produce ionization thereof. Also, instead of using bimetal thermostat switch 96, such a switch could be in the form of a heat expansive alloy adapted to disengage a pair of normally closed contacts upon a predetermined temperature being reached.

Now referring to FIG. 2 for a preferred modification of the present invention, a double anode Zener diode 89 is connected into the fire alarm circuit as shown. This produces a clipped sine wave of constant voltage regardless of line voltage fluctuations which energizes a neon lamp 90 through a current limiting resistor 87. Thus a constant level light source is provided by neon lamp 99. A photoconductive cell 93 is connected in series with a resistor 99 and the thermostat switch 96. It is clear that the resistor 99 could be a potentiometer to permit adjustment. The photoconductive cell 98 could be in the form of a cadmium sulfide or cadmium selenide cell. The photoconductive cell 98 is placed in proximity with the regulated light source from the neon lamp 90 so that light emitted from neon lamp 90 will strike the sensitive portion of the photoconductive cell 98. In the absence of a reduction of light output and light intensity striking the cell 98, the total series resistance of resistor 99 and cell 98 will be of a low enough value to prevent a build up of Voltage potential across capacitor 93 and the neon lamp 92 will not reach the ionization point to sound the alarm as heretofore explained.

The presence of smoke or other particles of a predetermined concentration would result in a sufficient reduction of light intensity reaching the photoconductive cell 98 and the resistance of the cell 98 would increase to the point to eifectively remove the shunt from capacitor 93 suificiently to permit a build up of voltage potential across the capacitor 93 sufiicient to cause ionization of the lamp 92 and sound a series of short duration alarms as heretofore explained.

If the surrounding temperature reaches a predetermined value, the thermostat switch 96 would open and the alarm would continue to sound in series even if the smoke thereafter dissipated.

It is to be noted that the particular circuitry disclosed provides a device in which, if the NEAR voltage is received while the fire alarm is sounding, the alarm would begin to be sounded in the uninterrupted alarm so that in elfect the NEAR signal takes priority. Further, care has been taken not to reduce the reliability of the NEAR receiver portion of the alarm device by adding the fire and smoke alarm portions to the device. The source of power for the fire alarm of FIG. 1 and the smoke detector-fire alarm of FIG. 2 are connected across the AC. side of the lines 14-15 and therefore if the components of these alarms should short circuit the operation of the NEAR portion of the device would not be aflfected. Also the neon lamp 92 through which the fire alarm circuits are connected to the NEAR alarm circuit provides more than one billion ohms of resistance in the standby condition of the device so that in this condition the circuits are effectively isolated.

Although we have described several embodiments of the present invention, it will be apparent to one skilled in the art that various other changes and modifications can be made without departing from the spirit of the invention as suggested by the scope of the appended claims.

We claim:

1. In an alarm circuit having a source of electrical power and means selectively imposing a predetermined actuation signal thereon, a multiple alarm device comprising:

(a) first detector means responsive only to said predetermined actuation signal,

(b) time delay means connected with said first detector means,

(c) a control circuit responsive to said time delay means,

(d) an alarm producing means operably connected with said control circuit, and

(e) second detector means including a constant light source and means adjacent said light source for sensing changes in the light intensity thereof,

(f) said second detector means including:

(1) means for actuating said control circuit upon said light intensity decreasing to a predetermined value, and

(2) a normally closed heat responsive switch, said switch being operable to close and actuate said control circuit upon being heated to a predetermined value.

2. The multiple alarm device of claim 1 wherein said constant light source is a gaseous lamp and said means for sensing changes in the light intensity thereof is a photoconductive cell.

3. The device as defined in claim 1 and in which said time delay means comprises:

(a) a capacitor,

(b) means discharging said capacitor at a predetermined rate upon said time delay means being activated, and

(c) means closing said first mentioned control circuit when said capacitor has discharged a predetermined amount.

4. The device as defined in claim 3 and in which said time delay means further comprises:

(a) a second capacitor being connected in parallel with said discharging means whereby upon receipt of said actuation signal said second capacitor immediately discharges,

(b) means electrically connecting said second capacitor and said first capacitor and a blocking diode disposed in said connecting means to prevent discharge of said first capacitor through said discharging means,

(c) means delaying the discharge of said first capacitor,

and

(d) said alarm producing means including switching means and said control circuit operably connected to said switching means and responsive to the delayed discharge of said first capacitor to actuate said switching means when said capacitor has been discharged a predetermined amount.

5. The device as defined in claim 3 and in which said means discharging said capacitor comprises:

(a) a resonant circuit including an inductor,

(b) a normally open discharge switch operable to be closed by said inductor only when said pretermined actuation signal is imposed upon said resonant circuit.

6. The device as defined in claim 3 and including (a) said alarm producing means including switching means and said control circuit operably connected to said switching means and responsive to the delayed discharge of said capacitor to actuate said switching means when said capacitor has been discharged a predetermined amount,

. (b) said control circuit including a transistor having its base electrically connected with said capacitor and its emitter-collector output side operably connected with said switching means whereby upon said capacitor discharging to a predetermined value said transistor is operable to actuate said switching means to sound an audible alarm.

7. In an alarm system having a source of electrical power and means imposing a predetermined actuation sign-al thereon, a multiple alarm device comprising:

(a) an alarm circuit including switching means and means for producing an audible alarm upon actuation of said switching means;

(b) energization means operable to activate said switching means after a predetermined time interval has elapsed from initial receipt of said actuation signal and including an energizing circuit and time delay means;

(c) said energizing circuit being operable to activate said time delay means only upon receipt of said predetermined actuation signal;

(d) said time delay means being operable to activate said switching means upon the lapse of a predetermined time interval after being activated by said energizing circuit;

(e) said time delay means including a capacitor, means for discharging said capacitor at a predetermined rate upon said delay means being activated and means for actuating said switching means when said capacitor is discharged a predetermined amount; and

(f) additional means for actuating said switching means including an energizing circuit and a heat responsive element;

(g) said heat responsive element being operable to actuate said switching means upon being heated to a predetermined value; and

(h) wherein said heat responsive element comprises:

(1) a normally closed bi-metal switch,

(2) a capacitor connected in parallel with said bi-metal switch, and

(3) a neon lamp having its input connected in series with said bi-metal switch and said capac1- tor and its output connected with said switching means.

8. In an alarm system having a source of electrical ower and means imposing a predetermined actuation gnal thereon, a multiple alarm device comprising:

(a) an alarm circuit including switching means and means for producing an audible alarm upon actuation of said switching means;

(b) energization means operable to actuate said switching means after a predetermined time interval has elapsed from initial receipt of said actuation signal and including an energizing circuit and time delay means;

(c) said energizing circuit being operable to actuate said time delay means only upon receipt of said predetermined actuation signal;

(d) said time delay means being operable to actuate said switching means upon the lapse of a predetermined time interval after being activated by said energizing circuit;

(e) said time delay means including a capacitor, means discharging said capacitor at a predetermined rate upon said delay means being activated and means for actuating said switching means when said capacitor has discharged a predetermined amount; and

(f) additional means means including an energizing circuit and a sponsive element;

(g) said heat responsive element being operable to actuate said switching means upon being heated to a predetermined value; and

(h) wherein said heat responsive element comprises.

(1) a normally closed expansive alloy switch,

(2) a capacitor connected in parallel with said expansive alloy switch, and

(3) a neon lamp having its input connected in series with said capacitor and said expansive alloy switch and its output connected with said switching means.

9. In an alarm system having a source of electrical power and means imposing a predetermined actuation signal thereon, a multiple alarm device comprising:

(a) an alarm circuit including switching means and means for producing an audible alarm upon actuation of said switching means;

(b) energization means operable to actuate said switching means after a predetermined time interval has elapsed from initial receipt of said actaution signal and including an energizing circuit and time delay means;

() said energizing circuit being operable to activate s-aid time delay means only upon receipt of said predetermined actuation signal;

(d) said time delay means being operable to actuate said switching means upon the lapse of a predetermined time interval after being activated by said energizing circuit;

(e) s-aid time delay means including a capacitor, means discharging said capacitor at a predetermined rate upon said delay means being activated and means actuating said switching means when said capacitor has discharged a predetermined amount; and

for actuating said switching heat re- (f) additional means for actuating said switching means including an energizing circuit and a heat responsive element;

(g) said heat responsive element being operable to actuate said switching means upon being heated to a predetermined value; and

(h) wherein said heat responsive element comprises:

(1) a positive temperature coeflicient thermistor,

(2) a capacitor connected in parallel with said thermistor, and

(3) a neon lamp having its input connected in series with said capacitor and said thermistor and its output connected with said switching means.

10. The alarm device as defined in claim 7 and in which said additional actuating means includes:

(a) a constant light source;

(b) means adjacent said light source and detecting changes in light intensity caused by particles such as smoke and the like adjacent said source; and

(c) means actuating said switching means upon said light intensity decreasing to a predetermined value.

11. The alarm device as defined inclaim 7 and in which said time delay means further comprises:

(a) a second capacitor being connected in parallel with said discharging means whereby upon receipt of said actuation signal said second capacitor immediately discharges;

(b) means electrically connecting said second capacitor and said first capacitor and a blocking diode disposed in said connecting means to prevent discharge of said first capacitor through said discharging means;

(0) means delaying the discharge of said first capacitor; and

(d) a control circuit operably connected to said switching means and responsive to the delayed discharge of said capacitor to actuate said switching means when said first capacitor has been discharged to predetermined amount.

12. The alarm device defined in claim 7 further comprising:

(a) a control circuit operably connected to said switching means and responsive to the delayed discharge of said capacitor to actuate said switching means when said capacitor has been discharged a predetermined amount,

(b) said control circuit including a transistor having its base electrically connected with said capacitor and its emitter-collector output side operably connected with said switching means whereby upon said capacitor discharging to a predetermined value said transistor is operable to actutae said switching means to sound an audible alarm.

13. The alarm device as defined in claim 7 in which the means discharging the capacitor at a predetermined rate comprises:

(a) a resonant circuit including an inductor; and

(b) a normally open discharge switch operable to be closed by said inductor only when said predetermined actuation signal is imposed upon said resonant circuit.

14. The alarm device as defined in claim 7 and in which said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means; and

(b) means including a heat responsive normally closed switch and a capacitor connected in parallel to the input of said neon lamp and operable to increase the voltage on the input of said neon lamp upon said heat responsive switch being opened to remove the shunt from said capacitor.

15. The alarm device as defined in claim 7 and in which said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means;

(b) means including light intensity responsive means operable to convert a decrease in light intensity to an increase in resistance; and

(c) a capacitor connected in parallel with said light intensity responsive means and connected in series with the input of said neon lamp.

16. The device as defined in claim 15 and in which said light intensity responsive means comprises a gaseous lamp and a photoconductive cell positioned adjacent said lamp.

17. The device as defined in claim 16 and including means conducting a constant voltage to said gaseous lamp.

18. The alarm device as defined in claim 8 and in which said additional actuating means includes:

(a) a constant light source;

(b) means adjacent said light source and detecting changes in light intensity caused by particles such as smoke and the like adjacent said source; and

() means actuating said switching means upon said light intensity decreasing to a predetermined value.

19. The alarm device as defined in claim 8 and in which said time delay means further comprises:

(a) a second capacitor being connected in parallel with said discharging means whereby upon receipt of said actuation signal said second capacitor immediately discharges;

(b) means electrically connecting said second capacitor and said first capacitor and a blocking diode disposed in said connecting means to prevent discharge of said first capacitor through said discharging means;

(c) means delaying the discharge of said first capacitor;

and

(d) a control circuit operably connected to said switching means and responsive to the delayed discharge of said first capacitor to actuate said switching means when said first capacitor has been discharged a predetermined amount.

20. The alarm device defined in claim 8 further comprising:

(a) a control circuit operably connected to said switching means and responsive to the delayed discharge of said capacitor to actuate said switching means when said capacitor has ben discharged a predetermined amount,

(b) said control circuit including a transistor having its base electrically connected with said capacitor and its emitter-collector output side operably connected with said switching means whereby upon said capacitor discharging to a predetermined value said transistor is operable to actuate said switching means to sound an audible alarm.

21. The alarm device as defined in claim 8 in which the means discharging the capacitor at a predetermined rate comprises:

(a) a resonant circuit including an inductor; and

(b) a normally open discharge switch operable to be closed by said inductor only when said predetermined actuation signal is imposed upon said resonant circuit.

22. The alarm device as defined in claim 8 and in which said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means; and

(b) means including a heat responsive normally closed switch and a capacitor connected in parallel tothe input of said neon lamp and operable to increase the voltage on the input of said neon lamp upon said heat responsive switch being opened to remove the shunt from said capacitor.

23. The alarm device as defined in claim 8 and in which said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means;

(b) means including light intensity responsive means operable to convert a decrease in light intensity to an increase in resistance; and

(c) a capacitor connected in parallel with said light intensity responsive means and connected in series with the input of said neon lamp.

24. The device as defined in claim 23 and in which said light intensity responsive means comprises a gaseous lamp and a photoconductive cell positioned adjacent said lamp.

25. The device as defined in claim 24 and including means conducting a constant voltage to said gaseous lamp.

26. The alarm device as defined in claim 9 and in which said additional actuating means includes:

(a) constant light source;

(b) means adjacent said light source and detecting changes in light intensity caused by particles such as smoke and the like adjacent said source; and

(c) means actuating said switching means upon said light intensity decreasing to a predetermined value.

27. The alarm device as defined in claim 9 and in which said time delay means further comprises:

(a) a second capacitor being connected in parallel with said discharging means whereby upon receipt of said actuating signal said second capacitor immediately discharges;

(b) means electrically connecting said second capacitor and said first capacitor and a blocking diode disposed in said connecting means to prevent discharge of said first capacitor through said discharging means;

(c) means delaying the discharge of said first capacitor; and

(d) a control circuit operably connected to said switching means and responsive to the delayed discharge of said first capacitor to actuate said switching means when said first capacitor has been discharged a predetermined amount.

The alarm device defined in claim 9 further comprising:

(a) a control circuit operably connected to said switching means and responsive to the delayed discharge of said capacitor to actuate said switching means when said capacitor has been discharged a predetermined amount,

(b) said control circuit including a transistor having its base electrically connected with said capacitor and its emitter-collector output side operably connected with said switching means whereby upon said capacitor dischanging to a predetermined value said transistor is operable to actuate said switching means to sound an audible alarm.

29. The alarm device as defined in claim 9 in which the means discharging the capacitor at a predetermined rate comprises:

(a) a resonant circuit including an inductor; and

(b) a normally open discharge switch operable to be closed by said inductor only when said predetermined actuation signal is imposed upon said resonant circuit.

30. The alarm device as defined in claim 9 and in which said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means; and

(b) means including a heat responsive normally closed switch and a capacitor connected in parallel to the input of said neon lamp and operable to increase the voltage on the input of said neon lam-p upon said heat responsive switch being opened to remove the shunt from said capacitor.

31. The alarm device as defined in claim 9 and in vhich said additional actuating means includes:

(a) a neon lamp having its output connected to said switching means and being operable upon a predetermined voltage build up at its input to conduct current and actuate said switching means;

(b) means including light intensity responsive means operable to convert a decrease in light intensity to an increase in resistance; and

(c) a capacitor connected in parallel with said light intensity responsive means and connected in series with the input of said neon lamp.

32. The device as defined in claim 31 and in which said light intensity responsive means comprises a gaseous lamp and a photoconductive cell positioned adjacent said lamp.

33. The device as defined in claim 32 and including 5 means conducting a constant voltage to said gaseous lamp References Cited by the Examiner UNITED STATES PATENTS 2,640,975 6/1953 Roe et a1. 2,982,950 5/ 1961 Boyle 340-227 3,035,251 5/ 196 2 Inderwiesen 3403 1 0 X 3,148,365 9/1964 Voigt et a1 340220 X 15 NEIL C.READ, Primary Examiner.

R. M. ANGUS, D. YUSKO, Assistant Examiners. 

1. IN AN ALARM CIRCUIT HAVING A SOURCE OF ELECTRICAL POWER AND MEANS SELECTIVELY IMPOSING A PREDETERMINED ACTUATION SIGNAL THEREON, A MULTIPLE ALARM DEVICE COMPRISING: (A) FIRST DETECTOR MEANS RESPONSIVE ONLY TO SAID PREDETERMINED ACTUATION SIGNAL, (B) TIME DELAY MEANS CONNECTED WITH SAID FIRST DETECTOR MEANS, (C) A CONTROL CIRCUIT RESPONSIVE TO SAID TIME DELAY MEANS, (D) AN ALARM PRODUCING MEANS OPERABLY CONNECTED WITH SAID CONTROL CIRCUIT, AND (E) SECOND DETECTOR MEANS INCLUDING A CONSTANT LIGHT SOURCE AND MEANS ADJACENT SAID LIGHT SOURCE FOR SENSING CHANGES IN THE LIGHT INTENSITY THEREOF, 